Considering the recent plastic loads in water bodies we studied the aggregation, charging, and aggregate strength of polyethylene microsphere (PEM) particles in the presence of natural organic matter (NOM) as a function of KCl and CaCl₂ concentrations. We used the Suwannee river humic acid (SRHA) as NOM and PEM as microplastics. The aggregation was triggered in the presence of CaCl₂ solutions more effectively than KCl due to the divalent bridging and strong electrostatic attraction between Ca²⁺ and SRHA as well as between PEM particles. We found that the maximum aggregate strength around 1.87 nN in the presence of 100 mg/L SRHA at 0.5 M CaCl₂ solution. The aggregate strength of PEM particles in the KCl solution was lower than that of CaCl₂ solution, manifesting the more effective bridging flocculation and divalent bridging due to the Ca²⁺ ions.

Graphic Abstract

中文翻译：

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天然有机物存在下塑料微粒的聚集和聚集强度：离子价的影响

考虑到最近在水体中的塑性载荷，我们研究了在存在天然有机物（NOM）的情况下，聚乙烯微球（PEM）颗粒的聚集，带电和聚集强度与KCl和CaCl ₂浓度的关系。我们将Suwannee河腐殖酸（SRHA）用作NOM，将PEM用作微塑料。由于Ca ²⁺与SRHA之间以及PEM颗粒之间的二价桥接和强静电吸引，在CaCl ₂溶液存在下比KCl更有效地引发聚集。我们发现在0.5 M CaCl ₂下存在100 mg / L SRHA时，最大聚集强度约为1.87 nN解。PEM颗粒在KCl溶液中的聚集强度低于CaCl ₂溶液，表明由于Ca ²⁺离子，桥絮凝和二价桥键更有效。

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